homework vs revisal

homework

noun
  • Something which one is encouraged to learn or study on one's own. 

  • Exercises assigned by a teacher to a student which review concepts studied in class. 

  • Sexual intercourse. 

revisal

noun
  • The act of revising; a revision. 

How often have the words homework and revisal occurred in a corpus of books? (source: Google Ngram Viewer )